Another speedo problem - but heat related!

[Troogly]

There seems to be a flurry of speedo problems at the moment.... I had some earlier in the year and thought I had had my dose of it. Not so. I now have another.

Speedo performs fine when engine is cold. Then, after about 10 mins or so it will just read zero mph. The odometer stops turning too. When I leave the car to cool right down, it will be fine again - but repeats the cycle.

I've also noticed that when the speedo is reading zero and I dip the clutch, the engine does cut out quite often as the revs fall off.

I'm thinking that this is probably a transducer problem. Not picking up a signal to send to speedo and also not indicating road speed properly for the ECU?

Strange though that when cold / cool everything is fine - but when warm it all starts to fail. Are these the symptoms of a transducer breaking down? I have a 92 pre-cat so the transducer is an early type (not one of these with an adjustable air gap).

All help appreciated! Thanks

[Troogly]

OK - further investigation suggests this is transducer related. But I understand transducers can be 4-pulse or 8-pulse units. Any idea what type I need for a '92 4.3 pre-cat?

All help welcomed

Thanks

[Ant.]

Troogly said:

OK - further investigation suggests this is transducer related. But I understand transducers can be 4-pulse or 8-pulse units. Any idea what type I need for a '92 4.3 pre-cat?

All help welcomed

Thanks

Yes, either a 4 or 8 pulse!!!

It has been a long time since I did mine, and I think mine is a 4 pulse.

Unfortunately the only sure way is to pull it out.
Use an analogue multi-meter and turn it slowly and count the pulses per rev.

[scoule]

I did wonder if the connectors were different for the 4 and 8 pulse models? I bought an SD1 unit for mine initially (and swapped the 2 pin to a 3 pin connector) but it caused the speedo to read double. Why type of connector is on yours? Are all Grifs on the 3 pin?

They also seem to be coloured orange, black or red, which I believe relates to the number of pulses somehow!

The failing when hot symptoms were the same on my early Grif 500 until I replaced the sensor.

Edited by scoule on Tuesday 25th August 16:03

[Troogly]

Thanks for the advice..... not sure what type I have though. I'll have to pull it off and take it from there I think.